1. Field of the Invention
Embodiments of the present invention relate to, but are not limited to, electronic devices, and in particular, to the field of electronic device packaging.
2. Description of Related Art
As electronic equipment such as laptops and mobile phones become smaller, electronic packages that may be contained in these devices are likewise becoming smaller. One approach for reducing the size of electronic packages includes stacking two or more chips or dice in these packages. Each of these dice may be, for example, a processor, input/output device, graphical co-processor, a digital signal processor, nonvolatile and/or volatile memory, and the like.
In some situations, the stacked dice are spaced apart for various reasons including, for example, to prevent wire bonds that may couple an underlying die to a package substrate from being damaged by the overlying die or preventing the dice from being in direct contact with each other. In stacked-chip packages in which at least the same size or bigger die is placed on top of another smaller or equal-sized die, spacers are typically placed between the dice to maintain a certain gap between the dice.
FIG. 1 depicts a conventional electronic package with multi-stacked chips or dice. In this electronic package 100, a first die 102 and a second die 104 are stacked on top of a substrate 106. Each of the dice 102 and 104 is electrically coupled to the substrate 106 via wire bonds 108. The first die 102 is further coupled to the substrate (or die) via an adhesive 110. The second die 104 is coupled to the first die via adhesives 112 and a spacer, in this case, a plate spacer 114. Note that in this electronic package, the first die 102 is smaller than the second die 104. That is, the second die 104 having about the same size (may even be slightly smaller) or bigger than the first die 102 relative to at least one lateral or horizontal direction (i.e., parallel to the first and second die surfaces 115), the same direction, for example, where wire bonds 108 are attached to the first die 102. Although not depicted in FIG. 1, circuitry components such as transistors are typically located in the central portion of the active (top) surfaces of the first and second dice 102 and 104 while the peripheral portions of the active surfaces are typically dedicated to bonding pads and bond wires. The spacer 114 and adhesives 112, in this electronic package 100, assures that there is sufficient space between the first and second dice so that the wire bonds of the first die do not come in contact with the second die. The spacer 114 may be comprised of silicon or organic material such as a polyimide.
FIG. 2 depicts another electronic package with multi-stacked chips or dice. However, in this electronic package 200, instead of a plate spacer, spherical spacers 202 are employed to assure that the two dice maintain sufficient separating space. Such spacers 202 in adhesive 112 are typically placed at the central portion of the active surface 204 of the first die 102 away from the periphery of the active surface 204 where the wire bonds 108 are generally coupled to the first die 102. The spherical spacers 202 may be made of polymer materials to prevent damage to the active surface of the first die 102.